A bearing shell of this class for ball and socket joints, especially for motor vehicles, is known from DE 29722507 U1. DE 29722507 U1 discloses a bearing shell, which has slots for elastic deflection during the mounting of a joint ball in the bearing shell, the slots extend essentially in the direction of the central axis of the bearing shell. The inner walls of the bearing shell have groove-like depressions, which are used as grease depots for lubricating the ball and socket joint. Spacer nubs are provided on the outer walls of the bearing shell, which preset the position of the bearing shell in the ball and socket joint housing. The spacer nubs generate a pretension, however slight, after insertion into the ball and socket joint housing due to the additional material, which presses the bearing shell against the joint ball due to being supported on the ball and socket joint housing. Pretensioning of the bearing shell in certain areas is definitely desirable, because this makes it possible for the joint ball not to be lifted off from parts of the bearing shell even under load, so that the entire contact surface is available for the transmission of torques in the joint. However, the pretension brought about by the spacer nubs on the outer sides of the bearing shell acts on the entire bearing shell or the mounted joint ball and consequently also in areas in which such a pretension counteracts the actual task of the ball and socket joint, or leads to increased wear in certain areas, and thus shortens the service life of the ball and socket joint. At the same time, the space needed for installation is increased.
DE 19932789 A1 discloses a ball and socket joint in which the joint ball is enclosed in a manner adapted to the direction of the load to increase the transmission of forces without requiring a larger space for installation. The areas of the joint ball that are loaded more heavily due to the direction of the force, surround the bearing shell more than the less heavily loaded areas. However, the bearing shell must be lengthened in this embodiment to mount the joint ball in the bearing shell, which is equivalent to a great mounting effort as well as a high load on the material, which may lead to rupture of the bearing shell.
The bearing shells according to DE 19932789 A1 as well as DE 29722507 U1 are made homogeneously from a plastic by injection molding. This design leads in practice to the problem that if an inexpensive plastic is used, it is tribologically well suited in the unreinforced form but does not have sufficient strength, or it has good strength properties due to fiber reinforcement. Good strength properties are, however, equivalent to a loss of the tribological properties in case of inexpensive plastics. Pretensioning of the bearing shell to achieve better transmission of forces also cannot be achieved with these plastics because of the lack of flexibility.